Atomic Force Microscopy

基于原子力显微镜二维材料和异质结构特性表征

Learn more about how atomic force microscopy can be used to better understand 2D materials


Gain a Deeper Understanding of 2D Materials and their Properties Using AFM 

During this webinar, experts discuss how atomic force microscopy (AFM) can be effectively leveraged to understand the structure and properties of 2D materials.

This webinar comprises three presentations:

  • Bede Pittenger, PhD (Bruker), reviews a broad assortment of AFM-based modes and how they can be used to understand 2D materials and heterostructures.
  • Mihir Pendharkar, PhD (Stanford University), discusses the development of torsional force microscopy to image moiré superlattices in Van der Waals materials.
  • Mario Lanza, PhD (King Abdullah University of Science and Technology), presents about the nanoelectrical properties of the 2D layered material hexagonal boron nitride.

Webinar Summary

Two-dimensional materials have recently been of increasing interest due to observations of their novel optical, mechanical, and electrical properties. Twisted multilayers create moiré superlattices where the properties change with twist angle. Scanning probe microscopy (SPM) methods like atomic force microscopy (AFM) and scanning tunneling microscopy (STM) have proven to be extremely useful in characterizing and understanding these materials due to their high resolution and sensitivity to various different sample properties. In this webinar, we discuss:

  • Commonly used SPM modes for identification and characterization of 2D materials
  • Recent advancements in consistency of high-resolution 2D material mapping
  • Characterization of nanoelectrical properties in 2D materials
  • Influence of the fabrication process on 2D material properties

Find out more about the technology featured in this webinar or our other solutions for AFM-Based Characterization:

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Presentations Abstracts

Presenter Presentation Title Abstract
Bede Pittenger, Ph.D. Probing 2D materials with the power of AFM Atomic Force Microscopy was one of the first methods applied to the study of graphene and continues to be a powerful tool for 2D material research in general. Identifying and characterizing single layers and multilayers is routine, while crystal orientation can often be determined with the proper choice of mode and probe. Since the AFM probe can act as a nanoscale electrode, it is possible to directly measure electrical properties of these materials at the relevant length scales between 1 and 100nm. The AFM probe can also be used for nanomanipulation, allowing device fabrication by cutting, folding, or oxidation. In this webinar, we review an assortment of AFM based modes and discuss how they can be used to better understand 2D materials and heterostructures.
Mihir Pendharkar, Ph.D. Torsional Force Microscopy of Van der Waals Moirés and Atomic Lattices An interlayer twist between two layers of the same Van der Waals (VdW) material (like twisted bilayer graphene (tBG)) creates moiré superlattices with period proportional to the local interlayer twist angle and strain. Moiré patterns are also formed when two atomically thin, dissimilar materials, are placed on top of each other (like graphene on hBN); the moiré period now being sensitive to the difference in the two lattice constants, and their interlayer twist and strain. The moiré period can vary from sub-nanometers to microns in common VdW heterostructures and techniques to directly visualize individual moiré unit cells, over areas as large as common opto-electronic devices (>microns), in air, at room temperature, without extensive sample preparation are scarce. Here, we introduce Torsional Force Microscopy (TFM) - an AFM based technique relying on the torsional resonance of an AFM cantilever - to image moiré superlattices in VdW materials [1]. TFM is sensitive to dynamic friction at the tip-sample interface and hence does not require extensive sample preparation (including nanofabrication) or electrical bias between the tip and the sample. We also find that TFM can reveal atomic lattices of common VdW surfaces like hBN and graphene and can also reveal subsurface moirés, in samples where more than one moiré may exist. TFM was tested to work on VdW heterostructures held on soft polymer stamps and on glass slides, validating its used as a rapid feedback tool in VdW device stacking. With a success rate in excess of 90% for imaging tBG moirés and near certainty of imaging atomic lattices of hBN, TFM should enable unprecedented control over VdW device design, fabrication and feedback.

[1] arXiv:2308.08814
Mario Lanza, Ph.D. Nanoelectronic characterization of hexagonal boron nitride using CAFM. In this webinar I will discuss about the nano-electronic properties of a two-dimensional (2D) layered material called hexagonal boron nitride (h-BN). This material is of special importance for the community because it has a wide band hap of 5.9 eV, and hence it can be used as dielectric in electronic devices, with a perfect van der Waals interface with 2D conductors (like graphene, MXene) and 2D semiconductors (like MoS2, WS2). I will show how the properties of h-BN change depending on the fabrication process followed, focusing specially in samples synthesized by chemical vapour deposition because that is the method preferred by the semiconductors industry. I will mainly show data collected via conductive atomic force microscopy, although I will complement it with that obtained via electron microscopy.

Speakers

Bede Pittenger, Ph.D., Sr. Staff Development Scientist, AFM Applications, Bruker Nano Surfaces

 

Dr. Bede Pittenger is a Senior Staff Development Scientist in the AFM Unit of Bruker's Nano Surfaces Business.  He received his PhD in Physics from the University of Washington (Seattle, WA) in 2000, but has worked with scanning probe microscopes for 25 years, building systems, developing techniques, and studying properties of materials at the nanoscale.  His work includes more than thirty publications and three patents on various techniques and applications of scanning probe microscopy.  Dr. Pittenger's interests span topics from interfacial melting of ice, to mechanobiology of cells and tissues, to the nanomechanics of polymers and composites.

Mihir Pendharkar, Ph.D., Postdoctoral Fellow at Stanford University

Mihir Pendharkar is a Q-FARM Bloch Postdoctoral Fellow at Stanford University working in the group of Prof. David Goldhaber-Gordon focusing on making 2D materials stacking more uniform, reproducible and repeatable. Mihir was previously a postdoctoral researcher at UC Santa Barbara where he also received his PhD and MS in Electrical and Computer Engineering specializing in epitaxy of superconductor-semiconductor heterostructures for applications in topological quantum computation.

Mario Lanza, Ph.D., Associate Professor of Materials Science and Engineering at the King Abdullah University of Science and Technology

Mario Lanza got the PhD in Electronic Engineering (with honors) in 2010 at the Autonomous University of Barcelona. In 2010-2011 he was NSFC postdoctoral fellow at Peking University, and in 2012-2013 he was Marie Curie postdoctoral fellow at Stanford University. In October 2013 he joined Soochow University as Associate Professor, and in March 2017 he was promoted to Full Professor. Since October 2020 he is an Associate Professor of Materials Science and Engineering at the King Abdullah University of Science and Technology (KAUST, in Saudi Arabia), where he leads a group formed by 10 PhD students and postdocs. His research focuses on how to improve electronic devices and circuits using 2D materials, with special emphasis on resistive switching applications. Prof. Lanza has published over 185 research articles, including 1 Nature, 2 Science, 6 Nature Electronics and multiple IEDM proceedings (among others), and has registered four patents – one of them granted with 1 million USD. Prof. Lanza has received multiple top distinctions, like the IEEE Fellow (among others), and he is a Distinguished Lecturer from the IEEE – Electron Devices Society. Prof. Lanza is the Editor-in-Chief of the journal Microelectronic Engineering (Elsevier), and he serves in the board of many other journals and international conferences, including IEEE-IEDM and IEEE-IRPS.